Recently, there has come to be extensively used an endoscope whereby an elongated insertable part can be inserted into a body cavity to observe an internal organ or the like within the body cavity or to make any curing treatment by using a treating tool inserted through a treating tool channel as required.
In the conventional endoscope, for example, an illuminating light emitted from a light source device outside a body is led into the body cavity through a light guide inserted through an insertable part and is radiated onto a tissue within the body cavity, the light reflected from the surface of the tissue is received and observed with the naked eye in an eyepiece part or is imaged by a television camera or the like to observe the tissue surface within the body cavity.
However, with such a conventional endoscope, the tissue interior state as, for example, the blood flowing state in the veins below the mucous membrane of the stomach or the minute structure of the vein has been substantially unable to be observed. Therefore, in the diagnosis or the like of a disease of the tissue interior, tissue has had to be collected by using a forceps, again analyzed in detail, examined and diagnosed. In such a diagnosis, it takes a very long time until the result of the diagnosis is made known and the result of the diagnosis by a presumption to some extent can not help being made known. The unrest given to the patient will be large, the diagnosing time will be long and the tissue taking position will hurt. These are various problems.
In the patent gazette of Japanese Patent Publication No. 21678/1979, there is disclosed a technique wherein an image is formed, within an imaging mechanism provided in an endoscope, by an illuminating light having passed through a tissue from outside a body so that a deep part of the wall within the body may be observed.
Also, in USP 4541438, there is disclosed a technique of detecting the presence of a cancer with a fluorescence comprising an induced light radiating means, an optical detecting means detecting a fluorescence emitted by a specific tumor marker and a displaying means operatively connected with the detecting means.
However, there are disadvantages that, in the case of the observation by inserting the imaging means in the above mentioned prior art examples, the size of the imaging means will be limited and the operation will be difficult.